Magnetically actuated and held ball armature switching devices



Ma'y 28, 1957 F. D. xEYNoLDS 2,794,178

MAGNETICALLY ACTUATED AND HELD BALL ARMATURE l SWITCHING DEVICES medApril 5, 1954 z sheets-sheet 1 IN V EN TOR. FFAA/C75 D b//VOLDS' @imfmmA TURA/5K5 REYNOLDS MAGNETICALLY ACTUATED AND HELD BALL ARMATURE May 28,1957 SWITCHING DEVICES 2 Sheets-Sheet 2 INVENToR. ,CAPA/V05 D Pim/OLD? ArfoeA/Ej/a Filed April 5, 1954 United States Patent MAGNETICALLY CTUATEDAND HELD BALL ARMATURE SWITCHING DEVICES Francis D. Reynolds, Seattle,Wash., assigner to Boeing Airplane Company, Seattle, Wash., acorporation of Delaware Appiication April 5, 1954, Serial No. 421,658

1d Caiins. (Cl. S40-147) This invention relates to a magneticallyactuated and held selective switching device and further to asequentially operated multiple switch unit selective switching devicebasically similar to the rotary multipole type disclosed in theccs-pending application of Leroy C. Perkins and Francis D. Reynolds,Serial No. 288,254, tiled May l6, 1952. The novel magnetic switchactuating and holding arrangement when embodied in a sequentiallyoperated multiple switch unit form as herein disclosed greatly reducesor eliminates mechanical wear relative to that experienced with a devicein which the switch elements are held in resiliently deflected actuatedposition by sliding against a rotary barrier member as in theabove-cited application. The present invention is herein illustrativelydescribed by reference to its presently preferred form, but it will bereadily appreciated that certain changes and modifications therein maybe made without departing from the essential features presented.

An object of this invention is to provide a low-cost highly sensitiverelay or selective switching device in which a magnetically actuatedarmature or movable element is held with great retentivity in any of aplurality of actuated positions so as to withstand unusually highacceleration forces tending to dislodge it. A related object is such arelay device wherein little or no wear of electrical contacts can occurand no failure of moving or flexible parts through extensive use as inthe case of ordinary relays. Still another object is such a relay devicein which a slight amount of wiping or rubbing action inherently takesplace between the electrical contact surfaces during relay actuation,thereby to establish a lowresistance electrical contact therebetween butto a degree insufficient to create a wear problem.

An individual relay or selective switching unit incorporating featuresof the invention in one form comprises a free or floating ferromagneticball as the magnetically actuated and held switching element and acombination of permanent magnetic and soft core electromagnet elements.The term permanent magnetic or like terms as herein used is intended toinclude continuously energized electromagnets as well as true permanentmagnets comprising magnetized elements having a high ldegree of magneticretentivity. in some applications of the invention it may be preferableto employ true permanent magnets such as Alnico magnets in the magneticfield structure of the relay device, whereas in other instances it maybe desirable to utilize an arrangement of electromagnets. In all casesthe ferromagnetic ball is retained in an interpole space wherein itremains in contact with one magnetic pole face and is magneticallyshifted into Contact with either of two additional pole faces adjoiningthe tirst by temporary magnetization of the ferromagnetic core system ofthe device, such ball being held by permanent magnetic flux in either ofsaid shifted positions.

With a permanent magnet of even moderate strength according topresent-day standards the ball armature of the switching device is heldin any actuated position with great retentivity, one reason for thisbeing that the ball V balls.

2,794,178 Patented May 28, 1957 ICC need not be large or massive and thepermanent magnetic flux creating the retaining force is concentratedlargely in or through the ball. Moreover, the process of magneticallyactuating the ball between positions inherently produces slight rotationthereof hence a wiping action of its surface on the pole faces intowhich it comes in contact, thereby affording good electrical contacttherebetween. u

ln both the copending patent application cited above and in thesequentially operated, multiple switch unit form of the presentinvention the switch contact elements are actuated electromagnetically,that is, by application of selective control impulses to the eldwindingof rotary flux concentrating means. The pulses are applied in timedrelation to mechanical scanning movement of the linx concentrating meanspast switch contact elements arranged in circular series relationshipfor sequential selective actuating purposes. ln said copendingapplication the magnetic iiux concentrator was mounted for rotation withan annular barrier member having a notch or open-A ing vin one edgethereof adjacent the flux concentrator, permitting the latter, if thenmagnetized, to attract through such opening any switch contact elementthen in registry with it. ln the absence of such magnetization at thetime of passing, the switch contact element would remain in itsnnactuated position on the original side of the rotary barrier memberor, if previously actuated, would return to unactuated position throughsaid opening by resilientV recoil. By applying a pulse of energizingcurrent to the magnetic field winding at the instant of such registrythe switch Contact element would be drawn against its own resilientforce through the opening and held on the opposite side thereofmagnetically for a period of time suiiicient to be trapped there by thebarrier members continuing rotation. The actuated switch contact elementf would thus remain trapped in sliding contact with the barrier memberthroughout the latters full rotation cycle, at the completion of whichit would return through the opening to the original side of the barriermember if the magnetic field winding were not again energized at thatinstant. Any practical number of switch contact elements could thus beactuated in sequential selective manner for decoding and memory ofsequential digital pulse commands in remote control applications, fordigital cornputer operations and generally for electrical switchingoperations in any of various types of apparatus. Such a device can bemade very compact and will be capable of replacing much more complex,bulky and expensive electronic switching apparatus necessary foraccomplishing essentially the same results. Moreover, by ordinarystandards applied to mechanical switching devices, the former devicecould be made in relatively durable form.

In accordance with the present invention there are substituted for theresilient ferromagnetic switch contact.

reeds an equal number of switch contact ferromagnetic A permanentholding magnet of annular form arranged to cooperate with selectivelymagnetizable iiux concentrators or soft core pole pieces causes theballs to be attracted and held individually in either of two positionsin which they bridge between magnetic pole faces as switch contactsurfaces. With this novel arrangement it is unnecessary to rely uponresilient deflection for switch contact movement, also the problem ofmechanical wear is eliminated, since in either of the two alternativepositions of the switch contact balls they rest against stationarysurfaces and there is no sliding contactsufficient to produce wear.

As a further feature of the sequentially operated multiple switch unitform, flux diverters or shorting bars are mounted in the spaces betweensuccessive sets of pole pieces to prevent magnetic flux set up in oneswitch unit from` straying into the adjoining unit and affecting theposition of the ball armatures cooperating in the latter.

These and other features, objects and advantages of the invention willbecome more fully evident from the following description by reference tothe accompanying drawings.

Figure l is a simplified and partially schematic side view of aselective switching device or relay incorporating features of theinvention, and Figures 2 and 3 are similar viewsV of the same `deviceunder different operating conditions.

Figure 4 is a corresponding view of a modiied form of the relay.

Figure 5Vis a perspective view of the sequentially operated multipleswitch unit form of the invention with a portion thereof broken away toreveal details of interior construction. Figure 6 is a similar viewwherein a different portion of the structure is broken away to revealstill other details. Figure 7 is a schematic or simplied sectional sideView taken along the axis of the device for illustrating a switchIContact ball in one switching position. Figure 8 is a view similar toFigure 2 in which the same switch contact ball is shown in its alternateswitching positions.

. Figure 9 is a simplified and sectional view of a modified shown inFigure 5 et seq.

Referring to Figure l, the U-shaped permanent magnets 1 and 2 haveopposing upper and lower pole faces lq, 2a and 1b, 2b respectively ofunlike polarity. Thus the upper pole face 1n is a north magnetic poleand the opposing pole face 2a, arranged generally parallel thereto, is asouth magnetic pole. A soft core 3a in the form of a non-retentiveferromagnetic bar comprising the core of electromagnet winding 3cooperates with the two permanent magnets. The bar 3a lies between thelower pole aces 1b and 2b and extends therefrom to a point adjacent aspace between the upper pole faces 1a and 2a such that its end face 3alies generally perpendicular to and mutually adjoining the pole faces 1aand 2a. An armature ball 4 of ferromagnetic material rests in contactwith the electromagnet core pole face 3rz and one of the permanentmagnet pole faces 1a or 2a.

In theA absence of energization of the electromagnet winding 3 byapplication of voltage to the input terminals 3b, the core 3d assumes apolarity opposite that of the permanent magnet poleV face contacted bythe ball 4. In effect the ferromagnetic coreV 3a constitutes a polepiece for said permanent magnet and the ball 4 is firmly retained bymagnetic attraction in contact with the poleV face 3a and theVparticular permanent magnet pole face. InV FigureV 1 the conductive ballbridges between the conductive pole faces la and Sa, thereby closing anelectric circuit between relay output terminals 5a and 5c connected tomagnet 1 and'co're" 3a, respectively. Energization of electromagnetwinding 3 with the polarity indicated in Figure 2 has no effect on theswitching position of ball armature 4 since it merely adds to thepermanent magnetic flux sustained in core 3a from permanent magnet 1.However, energization of electromagnet winding 3 with opposite polarity,if of sufficient magnitude, produ-ces magnetic flux in the reversedirection in the core 3a and thereby causes the pole face 3a to assume amagnetic polarity like that of the permanent magnet pole face 1a thencontacted by the ball (Figure 3). The ball is thus repelled by thelatter pole face and is attracted to the opposite permanent magnet poleface 2a. In transit the ball remains firmly in contact with theintermediate pole face. The ball is now magnetically retainedV in itsnew switching position closing a circuit between output terminals 5b and5c after the source of energy is removed from winding 3. Preferably theball 4 and the pole faces are plated with a highly conductive metal forestablishing low-resistance contacts` In the modification appearing inFigure 4 a different configuration is used for the permanent magnets andalso for the core of thel electromagnet. In this case the permapartiallyschematic axial arrangement of the device nent magnets 6a and 6bcomprise the end portions of an E magnet structure and have a commonpole (north, in the example) located generally intermediate the endsthereof. The face of this intermediately situated common pole iscontinuously contacted by the ball armature 7. The electromagnet winding8 in this instance is wound on the C shaped low-retentivityferromagnetic core 8a. The end faces of this electromagnet core aredisposed adjacent opposite sides of the above-mentioned permanent magnetpole face to be engaged alternately by the ball 7. The two end or southpole faces of the permanent E magnet lie close to the core at locationsback of the respective pole faces of the latter such that the oppositeend portions of the core 8a serve as pole pieces for the two permanentmagnets when the coil is unenergized. The core 8a is segmented andelectrical insulating material 8b is interposed between the segments asshown.

`Relay output terminals 9a ,9b and 9c are connected respectively to oneend segment of core Sa, to the E magnet and to the opposite end segmentof core Sa.

In the operation of the modified rclay appearing in Figure 4, theposition assumed by thc ball is dependent on the polarity of previousenergization of electromagnet winding S. The ball then contacts thatpole face of the core 8a which was given a polarity opposite that of theintermediately situated E magnet pole. in the example the latter pole isa north magnetic pole and the ball contacts this pole and the left-handor south pole of the core 8a. Energization of the winding 8 to reversethe polarity of the core 8a will cause the ball to be repelled andattracted to the right-hand pole of the core 8a. The ball remains ineither of its two alternate actuated positions when energization isremoved from the coil 8, since under that condition the magneticattraction of the ball to the core pole face being contacted by the ballat any instant is greater than that to the opposite core pole face dueto the greater concentration of magnetic fiux snstained in the former byvirtue of the low-reluctance path furnished by the ball 7.

In certain instances wherein electromagnet energizing conductors wouldbe a handicap the electromagnet means of the relay device can bereplaced by a ferromagnetic structure which is temporarily magnetized bypositioning of Ian external magnet in the vicinity of the `device inorder to pass ball actuatingy magnetic flux through the interpole spacein a sense causing the ball to shift to an alternate position.

Referring now to the multiple relay form involving sequential selectiveoperation as illustrated in Figures 5 et seq., there is shown a driveVunit 1f) which may be of Iany type suitable for rotating the switchdevice shaft 12V in the desired manner. Such rotation may beintermittent, continuous, or may occur by increments relative to thefixedv switch device casing 14, depending upon the requirements of aparticular application. The switch device casing is generallycylindrical and is formed by the annular permanent magnet 1'6 havingthree inwardly projecting flanges extending around the inside peripherythereof. These flanges are located respectively at top, bottom andintermediate positions heightwise of the cylindrical form. Theintermediate fiange 16e constitutes a magnetic south pole' in theexample, whereas the top and bottom flanges constitute magnetic northpoles, so as to set up two co-existing magnetic fields of generallyannular form inside the casing. Circular plates 18 `and 2t) ofinsulating material furnish top and bottom covers for the casing and areclamped' in position on the opposite end faces of the cylindricalpermanent magnet 16 by means of four clamp bolts 22 spaced equidistantlyaround the' circumference ofthe casing and passing through the web ofthe magnet. Journals 24 are received in central openings in therespective cover plates 18 and 20 for rotationally supporting theshaft12 extending/'along the axis of the casing. K

Two'ferromagnetic ux concentrator arms 26 and 28 are rigidly 'mountedonthe shaft 12 yto project at right angles therefrom in the same angulardirection at respective locations immediately adjacent the inside facesof the top and bottom cover plates 18 and 20. The shaft 12, or at leastthat portion of the shaft between the ux concentrator arms 26 is also offerromagnetic material. In the space, lengthwise of shaft 12, betweenthe ux concentrator arms is mounted a solenoid 30 surrounding the shaft12, but structurally supported from the casing in a manner to bedescribed so that the shaft 12 `and with it the arms 26 and 28 can berotated freely while the solenoid remains stationary. Two openings areprovided through the side of the permanent magnet through which theopposite ends of the insulated conductor 30a forming the solenoid mayproject for connection to a suitable source o-f energizing current.

The top and bottom insulating cover plates 18 and 20 have an equalnumber of holes 32 arranged in circular' sel-ties relationship and atcorresponding locations about the axis of shaft 12. These holes serve assupporting sockets receiving the cylindrical base portions 34a of thebarlilse ferromagnetic pole pieces 34 and of the magnetic flux divertingor shielding bars 35 located in alternate series arrangement with thepole pieces :in the annular space lying generally between the annularcasing magnet 16 and the peripheral wall of the solenoid shell 30b. Thebarlike magnetic pole pieces 34 are arranged in pairs, the two membersof each pair being aligned parallel to the axis of shaft 12 and beingeach of a projecting length less than half the distance between theinside faces of the cover plates 18 and 20 so as to leave open spaces orcavities between the projecting ends of the members of each such pair ofpole pieces. These intenpole spaces are adjoined by the inside face ofthe annular permanent magnet pole member 16a. Small ferromagnetic ballsor armature elements 36 are received in the respective interpole spaces35 and are free to move up and down in those spaces into and out ofdirect physical contact with the ends of the two pole pieces 3ft whilebeing in direct physical contact with the face of the annular pole 16e.Preferably these balls and also the three pole faces which they maycontact are silver plated for establishing good electrical contactsurfaces.

' The up er pole pieces of each pair (34) iand the upper ends of thelinx shielding bars 3S are secured to the top cover plate 18 by screws36 and washers 38 and the lower pole pieces and the lower ends of thebars 35 are similarly secured to the bottom cover plate 20. The screws36 serve as fastening elements for the connection of terminal lugs 40aof electrical conductors 4l) to the respective pole pieces and bars. Thepairs of pole pieces 34 thus rigidly mounted inside the switch devicecasing serve as the primary supportingy means Vfor the solenoid 3i).vThe solenoid coil is received inside a solenoid shell 30!) of insulatingmaterial having a cylindrical outer portion which is notched radially atthe locations of the pairs of pole pieces to accommodate such polepieces in therespective notches. Also, these notches, designated 30e',have radially inner surfaces which are not liat but have intermediateprojections 30d 'forming top and bottom shoulders against which the tipfaces of the two pole pieces abut when received in the notches 30C.However, the radial width of the pole pieces is greater than the extentof the projections 30d relative to the inner walls of the; notches 313Cso that the projections 30d do not completely occupy the interpolespaces but leave room for the free up and down movement of theferromagnetic switch contact balls 36 necessary for such balls to movebetween positions of contact with the top and bottom pole pieces 34associated respectively with them. The notches 30C receiving the xedpole pieces, and the projections 30d abutted bythe pole piece tipsprovide xed support for the solenoid shell` centrally in the housing 14@and thereby maintain the necessary open spaces inside the ends of theti housing for free rotation of the flux concentrator arms 26, 28 insidethe housing.

Two thin rings 42 and 44 of insulating material separate the radiallyouter faces of the pole pieces from the permanent magnet 14 and therebyelectrically insulate the respective pole pieces from such magnet. Sincethe cover plates 18 and 20 and the solenoid shell 30b are themselves ofinsulating material the pole pieces 34 are individually insulated fromeach other. The pole pieces serve as separately insulated electricalswitch contacts, and the permanent magnet 16 as a ground contact.

The radial length of the ferromagnetic llux concentrator arms 26 and 28is slightly less than the radial distance to the inside faces of thepole pieces 34, so that the latter do not interfere with free rotationof such arms when the shaft is turned. However, the distance separatingthe ends of the arms from the pole pieces is sufficiently small thatmagentic flux set up by energization of the solenoid 30 readilytraverses the gap and passes into and through the pole pieces. Themagnetic flux path attending energization of solenoid 30 with onepolarity is represented by the broken line F in Figure 7. In Figure 8the polarity of solenoid energization has been reversed with the resultthat the magnetic ux extends in the opposite direction, although in thesame path las shown in the preceding figure. ln the rst case (Figure 7)the lower pole piece of a particular pair becomes the north magneticpole, whereas in the latter instance (Figure 8) the upper pole piecebecomes the north magnetic pole. The ferromagnetic switch contact ball36 in the particular interpole space remains at all times in electricalcontact with the face of the intermediate flange 16e of the permanentmagnet 16. In effect, therefore, this switch contact ball constitutes amovable south pole extension of the permanent magnet 16, and when thesolenoid is energized with the polarity shown in Figure 7 the ball isdrawn downwardly 'into electrical contact with the associated lower polepiece, whereas if the solenoid is energized as inFigure 8 the ball is'drawn upwardly into contact with the upper pole pieces of the particularpair. 1n either case the ball bridges electrically between theintermediate flange of the permanent magnet casing 16 and one of thepole pieces of the pairs of pole pieces. The flux shielding bars 35located between successive switch units prevent magnetic flux set up inthe pole pieces of one unit by means of the ux concentrator arms 26, 28from fringing over into the space occupied by the ball armature ofadjacent units.

For most applications of the invention the permanent magnet 16 (or theface of the intermediate pole 16e contacted by the balls 36) will begrounded, as indicated at 16d. Thus, the effect of energizing thesolenoid in one sense or the other to draw a switch contact ball 36 intoelectrical contact with the upper or the lower pole piece 34 associatedtherewith will be to ground that pole piece, hence the electricalconductor 40 connected to the outer end thereof.

In the operation of the device, by rotating the shaft 12, hence the iiuxconcentrator arms 26 and 28, successively past the pairs of pole piecesand applying impulses of current to the solenoid 30 of one polarity orthe other in timed relation to registry of the tiux concentrators armswith the individual pairs of pole pieces, a selective switching actionis achieved. Once a switch contact ball 36 has been actuated into oneposition or the other, it will remain in that position due to theholding action of the permanent magnet 16, since the upper or lower polepiece 34 then being contacted by that ball becomes an effectiveextension of the north magnetic pole of the permanent magnet 16. Only by`energizing the solenoid 30 with the reverse polarity when the fluxconcentrator arms 26 and 28 are again in registry with the same pair ofpole pieces will the particular switch contact ball 36S .be moved intoits opposite switching position. The neces-4 7 sary magnetizing forceapplied by the solenoid 30 to the ux concentrator arms 26 and 28 forshifting` the balls 36 in the described manner is not suicient to changethe permanent magnetization of the casing magnet 16.

VIn the modified form of sequentially operated, multiple unit selectiveswitching device shown in Figure 9 the annular permanent magnet 16 isinside the structure and its magnetic pole anges 16a, 1617 and 16e faceoutwardly surrounded by the alternately arranged iiux shield bars 35 andsets of pole pieces 34. Moreover, magnetization of the annular permanentmagnet structure 16 is derived in this instance by continuousenergization of the two annular coils 16u and 16p received in therespective `annular grooves between the intermediate iiange 16c and theupper and lower iianges 16a and 16b. By loeating the series of polepieces and coacting ball armatures outside the magnetic structure theover-all diameter of the device may be reduced for a given minimumspacing achieved between successive sets of pole pieces. The coils 16uand 16p will be energized with the polarities illustrated in order toproduce the desired magnetic polarities of the permanent magnet iiangesas magnetic poles.

In either of the `forms shown in Figures and 9 the actuating coil of theelectromagnet (30 or 30') may be replaced by two coils, if desired, sothat erasure can be accomplished by a second coil instead of byreversing the polarity of a single coil.

As in the case of individual relays incorporating the invention (Figure1, for example) the minor amount of movement required of the switchcontact balls 36 to be attracted magnetically from one position to theother in the sequential selective switching operations of the multipleswitch unit device is not of such a nature as to produce any appreciablemechanical wear, yet slight wiping action of the balls is inherentlyproduced in each actuation thereof as desired for establishing goodelectrical contact. Thus the life expectancy of this modified form ofthe sequential selective switching device is potentially -greater thanthat in which the switch contact elements are not free ferromagneticballs but are resiliently iiexible reeds which must be held bymechanical means such as aV rotating barrier member sliding thereon inorder to retain them in actuated position throughout -a cycle ofoperation of the Idevice and which after repeated exures may tend tocrystallize or fatigue.

These and other advantages of the construction herein disclosed will beapparent to those skilled in the art. Moreover, it will be apparent thatvarious other arrangements and types of construction of the individualrelay version and the multiple switch unit sequential operating versionmay be produced within the teachings of the invention featuring thecombined temporarily magnetizable magnet means and permanent magnetmeans cooperating with a single ferromagnetic ball armature.

l claim as my invention:

1. A sequential selective switching device comprising a magnetic fluxconcentrator means, means mounting said flux concentrator means forrepetitive movement in a predetermined path, means selectivelyenergizable for magnetizing said flux concentrator means at selectedtimes during movement thereof along said path, a plurality of pairs ofmagnetic pole members stationed at successive locations along said pathfor individually sustaining in any such pair the magnetic iiux from saidmagnetic flux concentrator means when the latter is magnetized andsubstantially in registry with any such magnetic pole member pair,substantially to the exclusion of adjacent magnetic pole members, themembers of each such pair of magnetic pole members being separated toform an interpole space therebetween, and at least one of said polemembers having an electrically conductive pole face adjoining said spaceVand arranged to function as a switch contact element,v permanent magnetmeans arranged cooperatively with said pairs of magnetic pole members toform permanent magnetic iiux circuits including the respective polemembers and including said interpole spaces, said permanent magnet meansincluding an electrically conductive pole face immediately adjoiningeach of said interpole spaces and arranged to function as a switchcontact element cooperatively with said first-mentioned switch contactelements, and a plurality ofl unattached ferromagnetic armature elementsreceived in the respective interpole spaces for freedom of movementtherein to contact simultaneously said permanent magnet pole face andeither one of the associated magnetic pole members, each of saidarmature elements being magnetically attractable from either of theassociated magnetic pole members to the other magnetic pole member inaccordance with the direction of magnetic ux passing from said uXconcentrator member through such magnetic pole members, such armatureelement having an electrically conductive surface and being retained inposition contacting both a magnetic pole member and said permanentmagnetic pole face by the permanent magnetic attraction of saidpermanent magnet means.

2. The device dened in claim 1, wherein the ferromagnetic armatureelements comprise round balls of ferromagnetic material having a surfaceof electrically conductive material.

3. A sequential selective switching device comprising .a shaft mountedfor rotation, a pair of magnetic iiux concentrator arms projecting inlike directions from said shaft at locations spaced apart along thelength thereof for rotation with said shaft, a solenoid surrounding saidshaft and selectively energizable for magnetizing said liux concentratorarms at selected times during rotation thereof, a plurality of pairs ofmagnetic pole members arranged parallel to the axis of said shaft inpositions of alignment of the members of each such pair at successivelocations around the rotational path of said arms for individuallysustaining in any such pair the magnetic flux from said magnetic uxconcentrator arms when the latter are magnetized and substantially inregistry with any such magnetic pole member pair, substantially to theexclusion of adjacent magnetic pole members, the members of each suchpair of magnetic pole members being separated to form an interpole spacetherebetween, and at least one of said pole members having anelectrically conductive pole face adjoining said space and arranged tofunction as a switch contact element, permanent magnet means arrangedcooperatively with said pairs of magnetic pole members to form permanentmagnetic ux circuits including the respective pole members and includingsaid interpole spaces, said permanent magnet means including anelectrically conductive pole face immediately adjoining each of saidinterpole spaces and arranged to function as a switch contact elementcooperatively with said first-mentioned switch contact elements, and aplurality of unattached ferromagnetic armature elements received in therespective interpole spaces for freedom of movement therein to contactsimultaneously said permanent magnet pole face and either one of theassociated magnetic pole members, each of said armature elements beingmagnetically attractable from either of the associated magnetic polemembers to the other magnetic pole member in accordance with thedirection of magnetic ux passing from said flux concentrator armsthrough such magnetic pole members, such armature element having anelectrically conductive surface and being retained in positioncontacting both a magnetic pole member and said permanent magnetic poleface by the permanent magnetic attraction of said permanent magnetmeans.

4. The device defined in claim 3, wherein the ferromagnetic armatureelements comprise round balls of ferromagnetic material having a surfaceof electrically conductive material.

5. The device defined in claim 4, wherein the per marient magnet meanscomprises a magnetized annular member having three inwardly projectingannular pole elements extending around the inside periphery thereof atmutually spaced-apart locations along the length of said annular member,the two outside pole elements being of like magnetic polarity andopposite to the magnetic polarity of the intermediate pole element, saidintermediate pole element being the one `adjoining the interpole spacesand having the conductive pole face.

6. Switch means comprising, in combination, a circular series of pairsof magnetic pole elements separated from each other to define interpolespaces between the members of each such pair, annular permanent magnetmeans surrounding said magnetic pole element series and having anintermediately situated magnetic pole of one polarity with anelectrically conductive face adjoining said interpole spaces and furtherhaving two additional magnetic poles of a polarity opposite that of saidintermediately situated pole adjoining the respective magnetic poleelements of said pairs, thereby to include said respective magnetic poleelements in the two permanent magnetic field circuits existing betweensaid intermediately situated pole and the two additional magnetic poles,a plurality of ferromagnetic balls having electrically conductivesurfaces loosely received in the respective interpole spaces and beingyadapted for simultaneously contacting said intermediately situated poleconductive face and either of the adjoining magnetic pole elements, saidlatter elements likewise having electrically conductive pole facesengageable by said balls, means forming individual electricalconnections to lthe respective magnetic pole elements as switch contactelements cooperative with said intermediately situated magnetic poleconductive face as a common switch contact element, and selectivelyenergizable magnetizing means operable to scan said magnetic poleelement pairs in successive order and selectively magnetize the sametemporarily with flux of one direction or the other passed through theassociated interpole spaces and thereby move the ferromagnetic ballsfrom one magnetic pole element to the other depending on such iiuXdirection.

7. The switch means defined in claim 6, wherein the magnetizing meanscomprises a pair of ferromagnetic flux concentrator arms, aferromagnetic shaft supporting such arms for rotating inside thecircular series of magnetic pole element pairs, and selectivelyenergizable solenoid means surrounding said shaft for magnetizing thesame, hence said arms and magnetic pole elements instantaneouslyIadjacent said arms, by passage of current through said solenoid means.

8. Switch means comprising, in combination, a circular series of pairsof magnetic pole elements separated from each other to define interpolespaces between the members of each pair, annular permanent magnet meansarranged concentrically within said circular series of pairs of poleelements and having outwardly facing intermediately situated magneticpole means of one polarity with an electrically conductive faceadjoining said interpole spaces and further having two additionalmagnetic poles of a polarity opposite that of said intermediatelysituated pole adjoining the respective magnetic pole elements of saidpairs, thereby to include said respective magnetic pole elements in thetwo permanent magnetic eld circuits existing between said intermediatelysituated pole and the two additional magnetic poles, a plurality offerromagnetic balls having electrically conductive surfaces looselyreceived in the respective interpole spaces and adapted forsimultaneously contacting said intermediately situated pole conductiveface either of the adjoining magnetic pole elements, said latterelements likewise having electrically conductive pole faces engageableby said balls,

means forming individual electrical connections to the respectivemagnetic pole elements as switch contact elements cooperative with saidintermediately situated magnetic pole conductive face as a common switchcontact element, and selectively energizable magnetizing means operableto scan said magnetic pole element pairs in successive order andselectively magnetize the same temporarily with flux of one direction orthe other passed through the associated interpole spaces and therebymove the ferromagnetic balls from one magnetic pole element to the otherdepending on such flux direction.

9. Switch means comprising, in combination, a circular series of pairsof magnetic pole elements separated from each other to dene interpolespaces between the members of each pair, a series of magnetic fluxshielding elements interposed between respectively adjacent pairs ofmagnetic pole elements, annular permanent magnet means arrangedconcentrically with respect to said circular series of pairs of poleelements and having intermediately situated magnetic pole means of onepolarity with an electrically conductive face adjoining said interpolespaces and further having two additional magnetic poles of a polarityopposite that of said intermediately situated pole adjoining therespective magnetic pole elements of said pairs, thereby to include saidrespective magnetic pole elements in the two permanent magnetic fieldcircuits existing between said intermediately situated pole and the twoadditional magnetic poles, a plurality of ferromagnetic balls havingelectrically conductive surfaces loosely received in the respectiveinterpole spaces and adapted for simultaneously contacting saidintermediately situated pole conductive face either of the adjoiningmagnetic pole elements, said latter elements likewise havingelectrically conductive pole faces engageable by said balls, meansforming individual electrical connections to the respective magneticpole elements as switch contact elements cooperative with saidintermediately situated magnetic pole conductive face as a common switchcontact element, and selectively energizable magnetizing means operableto scan said magnetic pole element pairs in successive order andselectively magnetize the same temporarily with tiux of one direction orthe other passed through the associated interpole spaces and therebymove the ferromagnetic balls from one magnetic pole element to the otherdepending on such tiux direction.

l0. Selective switching apparatus comprising a rst electrical contactsurface, a ferromagnetic ball occupying a region adjacent said surface,permanent magnet means passing magnetic flux through said surface andsaid ball to attract said ball against said surface, two additionalsurfaces at least one of which comprises an electrical contact surfaceadjoining said region and disposed generally perpendicular to said firstsurface, on opposite sides of said ball at a relative spacing permittingcontact of said ball with only one of said additional surfaces at atime, two ferromagnetic elements defining magnetic ux paths contiguousto said two additional surfaces, respectively, and arranged to pass saidpermanent magnetic flux and electromagnet means energizable for passingmagnetic flux through said additional surfaces and said region in eitherof opposite senses to make either of said additional surfaces a northmagnetic pole and the other a south magnetic pole depending on thepolarity of energization of said permanent magnet means, thereby drawingsaid ball magnetically into Contact with one or the other of said twosurfaces to be held in contact therewith by said permanent magnet ux,said permarient magnet means comprising two permanent magnet elementscontiguous to the said two additional surfaces, respectively, and theelectromagnet means comprising a ferromagnetic core element contiguousto the tirstmen tioned surface and forming a magnetic flux path commonto said permanent magnet elements.

(References on following page) UNITED STATES PATENTS Potter Oct. 8, 1901Finnigan Jan. 25, 1916 Kettering July 25, 1916 Armstrong Mar. 22, 1938Harrison Aug. 26, 1941 Whittaker Feb. 2, 1943 Carpenter Dec. 3, 1946Buckingham Jan. 24, 1956 Buckingham Jan. 24, 1956 FOREIGN PATENTS FranceJune 14, 1911 Germany July 6, 1932 Germany Dec. 22, 1937

